The basic sequence: prepare the base, snap lines, nail from bottom to top

Laying shingles on a shed roof starts with a solid foundation and moves upward in overlapping rows. You begin by ensuring the roof deck (plywood or boards) is flat and find, then cover it with underlayment — usually 15-pound felt or synthetic roofing paper — which catches water that gets under the shingles. Once the underlayment is down and fastened, you snap chalk lines to keep rows straight, then nail shingles in place starting at the lowest edge and working toward the peak. Each row overlaps the one below it so water runs down and off rather than pooling or seeping in.

The entire process typically takes one to three days depending on shed size and roof pitch. A steep roof takes longer because you need more safety precautions and the work is slower. Most shed roofs are straightforward — either a single slope or a basic gable — which makes the job more straightforward than a house roof with valleys and dormers.

Key Takeaways

  • The roof deck must be flat, solid, and free of rot or soft spots before you start; any weak plywood or boards will cause shingles to fail prematurely.
  • Underlayment goes down first and must be fastened with cap nails or staples so it does not shift when you walk on it during shingle installation.
  • Shingles are nailed in overlapping horizontal rows starting at the eave and moving upward, with each row covering the nail heads of the row below.
  • Nail placement matters: standard three-tab shingles need four nails per shingle, placed in a specific zone to prevent wind lift and splitting.
  • Ridge shingles or cap shingles finish the peak and must overlap correctly to shed water away from the ridge line.

Preparing the roof deck and checking for damage

Before any shingles go down, walk the entire roof and check for soft spots, rot, or missing sections. Press on the plywood or boards with your foot or a hammer handle — if it gives or feels spongy, that section is compromised and must be replaced. Rot spreads quickly under shingles, so do not cover it up. If you find damaged areas, cut out the bad section and nail in new plywood or boards of the same thickness, making sure the seams fall on a rafter or support beam underneath.

The deck should be as flat as possible. Small bumps or dips are normal, but large waves or high spots will cause shingles to buckle or crack. If the roof is severely uneven, you may need to add shims or sand down high spots before proceeding. Check that all fasteners holding the deck are tight — loose boards will move under foot traffic and cause nails to back out of shingles.

Installing underlayment and drip edge

Underlayment is a water barrier that sits between the deck and the shingles. Roll it out horizontally, starting at the eave and working toward the peak. Overlap each row by at least 2 inches so water cannot run sideways under the seams. Fasten it with cap nails (large-head roofing nails) or a staple gun every 12 to 16 inches, and more often in windy areas. Do not leave it loose — it will bunch up and create lumps under the shingles.

At the eave edge, install a drip edge — a metal flashing that hangs over the gutter or fascia and directs water away from the wood. The underlayment goes on top of the drip edge at the eave, but underneath it at the gable ends. This overlap pattern ensures water runs off cleanly. Nail the drip edge every 12 inches with roofing nails.

Snapping chalk lines and laying the first row

Snap a horizontal chalk line 11 and 1/4 inches up from the eave edge. This is where the top of your first row of shingles will sit (standard three-tab shingles are 12 and 5/8 inches tall, so this leaves a 1 and 3/8 inch overhang). Use a chalk line tool — snap it tight so the line is straight and visible. This first line is critical because every row above it depends on it being level.

Lay the first shingle at the eave corner, aligned with the chalk line. Most roofers start with a half-shingle or cut the first shingle in half so that the seams in the second row fall in the middle of the first row's shingles — this staggers the seams and prevents water from running straight down through them. Nail the first shingle with four nails: two near the top and two in the slots between tabs. Then lay full shingles across the eave, nailing each one as you go. Shingles should butt tightly against each other with no gaps.

Nailing pattern and fastener placement

Each three-tab shingle gets exactly four nails, placed in a specific zone to prevent wind lift and splitting. The nails go in a horizontal line about 5 and 5/8 inches up from the bottom edge of the shingle, positioned just above the adhesive strip (if the shingle has one). On a three-tab shingle, this means one nail in each tab slot, roughly centered. Use roofing nails — typically 1 and 1/4 inches long — that are long enough to penetrate the deck by at least 3/4 inch but not so long that they poke through and create a leak point.

Drive nails straight in, not at an angle. The head should sit flush with the shingle surface, not sunk into it (which tears the asphalt) and not sticking up (which catches water). If a nail misses the deck or goes in crooked, pull it out and move it slightly — do not leave bad nails in place. Overdriven nails are one of the most common causes of premature shingle failure.

Laying subsequent rows and staggering seams

Snap a new chalk line 12 and 5/8 inches above the first row (the full height of a shingle). Lay the second row along this line, but start with a full shingle instead of a half — this staggers the seams. Continue across, nailing each shingle with four nails. Repeat this pattern: odd rows start with a full shingle, even rows start with a half shingle (or cut shingle). This staggering prevents water from flowing straight down through the seams.

As you work upward, check frequently that rows are staying level. Chalk lines can drift if the roof is not perfectly square, so snap a new line every two or three rows. Walk on the shingles carefully — step on the nailed portion, not the loose overhang, which can tear. Once shingles are nailed down, they are fairly durable, but fresh asphalt shingles are softer in warm weather and can be damaged by careless foot traffic.

Finishing the ridge and hip lines

When you reach the peak, the last full row of shingles will overlap the ridge line. Trim the shingles so they fit neatly at the peak — you can cut them with a utility knife. Then install ridge cap shingles (also called cap shingles), which are single tabs cut from standard shingles or sold as pre-made ridge caps. These fold over the peak and overlap like the field shingles, with each cap covering the nails of the one below.

Ridge caps are nailed with two nails per cap, placed so the next cap covers them. Start at one end of the ridge and work toward the other. At the final cap, fold it over and nail it down, then seal the exposed nails with roofing cement to prevent water from running under them. If your shed has a hip (a sloped edge where two roof planes meet), treat it the same way as the ridge — use cap shingles and overlap them from bottom to top.

Sealing and protecting the finished roof

Once all shingles and caps are nailed, walk the roof one more time and check for any nails that are sticking up, any shingles that are curling or not lying flat, or any gaps. If shingles are not adhering to each other (they should stick together once they warm up in the sun), you can lift the tab and explore a small dab of roofing cement underneath. Do not use too much — excess cement can trap moisture.

Asphalt shingles need a few days of warm weather to fully cure and bond. If you install them in cold weather, they may not seal properly until temperatures rise. Avoid walking on the roof for at least 24 hours after installation, and longer if the weather is cool. Once the roof is complete, keep gutters clean and check for any loose shingles or missing nails after storms.

Frequently Asked Questions

What size nails do I use for shed roof shingles?

Use roofing nails that are 1 and 1/4 inches long for standard asphalt shingles over plywood. The nail must penetrate the deck by at least 3/4 inch to hold properly. If your deck is thicker (such as 1-inch boards), use 1 and 1/2 inch nails instead. Always use galvanized or stainless steel nails to prevent rust.

Can I install shingles in cold weather?

Asphalt shingles are harder and more brittle in cold weather, which makes them prone to cracking and splitting during installation. They also do not seal properly until temperatures reach about 50 degrees Fahrenheit. If you must roof in cold weather, work slowly, avoid bending shingles sharply, and expect the seal to take longer to form once temperatures warm up.

How much overhang should shingles have at the eave?

Shingles should overhang the eave edge by 1 and 1/4 to 1 and 1/2 inches. This allows water to drip off the drip edge and into the gutter rather than running back under the shingles or down the fascia. If the overhang is too large, wind can lift the shingles; if it is too small, water may not clear the edge.

What do I do if I find rot under the shingles after I start?

Stop and remove the shingles from that area. Cut out the rotted section and replace it with new plywood or boards of the same thickness. Nail it securely, then re-install underlayment and shingles over the repair. Continuing over rot will only make the problem worse and cause the roof to fail prematurely.

Do I need to remove old shingles before laying new ones?

If the old shingles are in good condition and lying flat, you can roof over them — this is called a re-roof. However, if they are curled, missing, or damaged, remove them first. Roofing over bad shingles will not fix the underlying problems, and the new shingles may not lie flat or last as long.